Analysis of 16S rRNA gene sequence of nasopharyngeal exudate from healthy donors reveals changes in key microbial communities associated with aging

BackgroundFunctional or compositional perturbations of the microbiome can occur at different sites of the body and this dysbiosis has been linked to various diseases. Changes in the nasopharyngeal microbiome are associated to patients susceptibility to multiple viral infections, including COVID-19, supporting the idea that the nasopharynx may be playing an important role in health and disease. Most studies on the nasopharyngeal microbiome have focused on a specific component in the lifespan, such as infanthood or the elderly, or have other limitations such as low sample sizes. Therefore, detailed studies analyzing the age- and sex-associated changes in the nasopharyngeal microbiome of healthy people across their whole life are essential to understand the relevance of the nasopharynx in the pathogenesis of multiple diseases, particularly viral infections such as COVID-19. Results120 nasopharyngeal samples from healthy subjects of all ages and both sexes were analyzed by 16s rRNA sequencing. Nasopharyngeal bacterial alpha diversity did not vary in any case between age or sex groups. Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes were the predominant phyla in all the age groups, with several sex-associated differences probably due to the different levels of sex hormones between both sexes. Acinetobacter, Brevundimonas, Dolosigranulum, Finegoldia, Haemophilus, Leptotrichia, Moraxella, Peptoniphilus, Pseudomonas, Rothia, and Staphylococcus were the only 11 bacterial genera that presented significant age-associated differences. Other bacterial genera such as Anaerococcus, Burkholderia, Campylobacter, Delftia, Prevotella, Neisseria, Propionibacterium, Streptococcus, Ralstonia, Sphingomonas, and Corynebacterium appeared in the population with a very high frequency, suggesting that their presence might be biologically relevant. ConclusionsIn contrast to other anatomical areas such as the gut, bacterial diversity in the nasopharynx of healthy subjects remains very stable and resistant to perturbations throughout the whole life and in both sexes. Age-associated changes in taxonomic composition were observed at phylum, family, and genus levels, as well as several sex-associated changes probably due to the different levels of sex hormones present in both sexes at certain ages. Our results provide a complete and valuable dataset that will be useful for future research aiming for studying the relationship between changes in the nasopharyngeal microbiome and susceptibility to or severity of multiple diseases, including COVID-19.